The three jaggers had gone to lunch at the only Mexican restaurant in Bristol. As is known, many Mexican cuisine dishes contain raw onion and raw onion returns, that is, it causes bad breath.

That is why Micky-boy made this comment so super fun.
It is known to all that the breath itself does not sing because the breath is simply the air that escapes from the lungs but sometimes it can be contaminated during its passage through the pestilent mouth, either raw onion, garlic, red pepper, tobacco … etc. It is on these occasions that one says that the breath “sings” in a metaphorical sense, as if it meant that it is not in its natural state, free from any smelly contagion.
Occasionally, products can be used to make the breath a determined odor. A clear example would be caramel mint, which would also be used to try to hide some of the odors that could be called “singers.”
In Micky-boy, using itHis undeniable ingenuity and prodigious sense of humor created a link between the musical thread and the song of breath, as singing is a form of music. The proven lack of musical thread on the plane would be replaced by the supposed song of his breath.